From 0d1e5ef1192acd75d476ecfebd92193e6b6d2880 Mon Sep 17 00:00:00 2001
From: Surma <surma@surma.link>
Date: Fri, 15 Feb 2019 14:20:06 +0000
Subject: [PATCH] Simplify rotation code to 90deg only

---
 codecs/rotate/rotate.rs   |  93 +++++++++-----------------------------
 codecs/rotate/rotate.wasm | Bin 533 -> 353 bytes
 2 files changed, 21 insertions(+), 72 deletions(-)

diff --git a/codecs/rotate/rotate.rs b/codecs/rotate/rotate.rs
index 4a766c1e..ccac2ef2 100644
--- a/codecs/rotate/rotate.rs
+++ b/codecs/rotate/rotate.rs
@@ -4,87 +4,36 @@ use std::slice::from_raw_parts_mut;
 // https://rustwasm.github.io/book/reference/code-size.html
 #[cfg(not(debug_assertions))]
 #[inline]
-pub fn unwrap_abort<T>(o: Option<T>) -> T {
-    use std::process;
+fn unwrap_abort<T>(o: Option<T>) -> T {
     match o {
         Some(t) => t,
-        None => process::abort(),
+        None => std::process::abort(),
     }
 }
 
-// Normal panic-y behavior for debug builds
 #[cfg(debug_assertions)]
-unsafe fn unchecked_unwrap<T>(o: Option<T>) -> T {
+fn unwrap_abort<T>(o: Option<T>) -> T {
     o.unwrap()
 }
 
 #[no_mangle]
-fn rotate(input_width: isize, input_height: isize, rotate: isize) {
-  let mut i = 0isize;
-
-  // In the straight-copy case, d1 is x, d2 is y.
-  // x starts at 0 and increases.
-  // y starts at 0 and increases.
-  let mut d1_start: isize = 0;
-  let mut d1_limit: isize = input_width;
-  let mut d1_advance: isize = 1;
-  let mut d1_multiplier: isize = 1;
-  let mut d2_start: isize = 0;
-  let mut d2_limit: isize = input_height;
-  let mut d2_advance: isize = 1;
-  let mut d2_multiplier: isize = input_width;
-
-  if rotate == 90 {
-    // d1 is y, d2 is x.
-    // y starts at its max value and decreases.
-    // x starts at 0 and increases.
-    d1_start = input_height - 1;
-    d1_limit = input_height;
-    d1_advance = -1;
-    d1_multiplier = input_width;
-    d2_start = 0;
-    d2_limit = input_width;
-    d2_advance = 1;
-    d2_multiplier = 1;
-  } else if rotate == 180 {
-    // d1 is x, d2 is y.
-    // x starts at its max and decreases.
-    // y starts at its max and decreases.
-    d1_start = input_width - 1;
-    d1_limit = input_width;
-    d1_advance = -1;
-    d1_multiplier = 1;
-    d2_start = input_height - 1;
-    d2_limit = input_height;
-    d2_advance = -1;
-    d2_multiplier = input_width;
-  } else if rotate == 270 {
-    // d1 is y, d2 is x.
-    // y starts at 0 and increases.
-    // x starts at its max and decreases.
-    d1_start = 0;
-    d1_limit = input_height;
-    d1_advance = 1;
-    d1_multiplier = input_width;
-    d2_start = input_width - 1;
-    d2_limit = input_width;
-    d2_advance = -1;
-    d2_multiplier = 1;
-  }
-
-  let num_pixels = (input_width * input_height) as usize;
-  let in_b: &mut [u32];
-  let out_b: &mut [u32];
-  unsafe {
-    in_b = from_raw_parts_mut::<u32>(4 as *mut u32, num_pixels);
-    out_b = from_raw_parts_mut::<u32>((input_width * input_height * 4 + 4) as *mut u32, num_pixels);
-  }
-
-  for d2 in 0..d2_limit {
-    for d1 in 0..d1_limit {
-      let in_idx = (d1_start + d1 * d1_advance) * d1_multiplier + (d2_start + d2 * d2_advance) * d2_multiplier;
-      *unwrap_abort(out_b.get_mut(i as usize)) = *unwrap_abort(in_b.get(in_idx as usize));
-      i += 1;
+fn rotate(width: usize, height: usize, _rotate: usize) {
+    let num_pixels = width * height;
+    let in_b: &mut [u32];
+    let out_b: &mut [u32];
+    unsafe {
+        in_b = from_raw_parts_mut::<u32>(4 as *mut u32, num_pixels);
+        out_b = from_raw_parts_mut::<u32>((num_pixels * 4 + 4) as *mut u32, num_pixels);
+    }
+
+    let new_width = height;
+    let _new_height = width;
+    for y in 0..height {
+        for x in 0..width {
+            let new_x = (new_width - 1) - y;
+            let new_y = x;
+            *unwrap_abort(out_b.get_mut(new_y * new_width + new_x)) =
+                *unwrap_abort(in_b.get(y * width + x));
+        }
     }
-  }
 }
diff --git a/codecs/rotate/rotate.wasm b/codecs/rotate/rotate.wasm
index a3ba42655643fae2907b391a42b85864db526183..4ff666499b95b845874e0c3ea1816d7764f95e62 100755
GIT binary patch
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